Shock absorbers of this type are generally known and used, for instance, in various sorts of vehicles, such as cars, trucks and trains, although shock absorbers are also applied in other applications. Application in cars is well known. The shock absorbers are set to a specific damping behavior by the design and implementation of the flow and valve arrangement provided in between the cylinder chambers. Such design and implementation determines important parameters governing the damping behavior. When applied in a car, the parameters may be set such as to provide a stiff damping behavior, which is often referred to as a sportive setting, or to provide a soft damping, which is often referred to as a comfortable setting. Damping of wheel and car body movements can be in conflict, especially in the comfort setting, since eigenfrequencies of car body and wheel are quite different. The eigenfrequency of a car body is about 1 Hz and of the wheel about 11 Hz, which sets different requirements for (critical) damping. On the one hand a wheel should be able to follow the road surface while driving, which requires low damping, but on the other hand the car body should better not be allowed to swing, which requires high damping.
It is desired to have a shock absorber, or damper, that can be set to both a sportive and a comfortable setting, as required or desired. Electronic controls have been proposed for influencing the damping behavior. Such electronically-controlled shock absorbers are complex, costly and susceptible to malfunction in case of failure of the electronics. It requires fast sensors, computation and control units and corresponding wiring of the various electronic parts.